Effect of CdO on physical and optical properties of cadmium silicon bismuthate glasses

Meenakshi bhutani, Ajay Shankar, Ashish Agarwal, Satish Khasa

Abstract

Glasses with composition xCdO.ySiO2.yBi2O3 (with x=0, y=50; x=10, y=45; x=20, y=40 and x=30, y=35 mol %) were synthesized using conventional melt quenching technique. The variation in physical and optical properties has been studied as a function of CdO content in cadmium silicon bismuthate glasses. The amorphous nature was confirmed by X- ray diffraction. The changes in physical properties like density, molar volume, oxygen packing density (OPD) and crystalline volume (Vc) shows structural modification on addition of CdO. Thermal properties like glass transition temperature (Tg) and crystallization temperature (Tp) were determined by differential scanning calorimetry (DSC) and values of Tg were found to increase while that of Tp decrease as substitution of CdO increases. The fundamental absorption edge has been found out from the optical absorption spectra. The optical band gap, Eg, for indirect allowed transitions has been determined and its value lies between 2.70-2.76 eV and found to decrease with increase in CdO content. The systematic study of structure was carried out by Infrared and Raman spectroscopy which shows that these glasses are made of [BiO3], [BiO6] and [SiO4] structural units and both symmetric as well as asymmetric stretched vibrations of Si-O bonds in SiO4 were present